Increasing the limit of keys in a usage plan in AWS API Gateway

I have some was api's deployed in AWS API Gateway, and there is a key named "x_key", Since keys can be added to multiple usage plans , this key is also added to 10 such plans. But when I try to add it onto the 11th usage plan it throws error similar to the following

An error occurred: MyServiceKey - Resource handler returned message: "The Usage Plan limit for API Key x_key has been reached. The limit is 10 (Service: ApiGateway, Status Code: 400, Request ID: 2xxxxxd5-baxx-4xx6-rx00-dxxxxxxx65f)" (RequestToken: xxxx00a4-x0x0-0000-000x-f48xxxxxxx8, HandlerErrorCode: InvalidRequest).

Before asking to the forum, I tried to find this limit in the console, but was unable to do so. Also, I checked the quota and limits documentation from the AWS but no help.